use std::env;
use std::error::Error;
use std::fs;
#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn case_sensitive() {
        let query = "duct";
        let contents = "\
Rust:
safe, fast, productive.
Pick three.
Duct tape.";
        assert_eq!(vec!["safe, fast, productive."], search(query, contents))
    }
    #[test]
    fn case_insensitive() {
        let query = "rUsT";
        let contents = "\
Rust:
safe, fast, productive.
Pick three.
Trust me.";
        assert_eq!(
            vec!["Rust:", "Trust me."],
            search_case_insensitive(query, contents)
        )
    }
}

#[derive(Debug)]
pub struct Config {
    query: String,
    filename: String,
    case_sensitive: bool,
}
impl Config {
    //&[T]：表示一个切片，通常用于引用数组或 Vec 的一部分。
    pub fn new(mut args: std::env::Args) -> Result<Config, &'static str> {
        args.next();
        let query = match args.next() {
            Some(arg) => arg,
            None => return Err("Didn't get a query string"),
        };
        let filename = match args.next() {
            Some(arg) => arg,
            None => return Err("Didn't get a file name"),
        };
        let mut case_sensitive: bool = env::var("CASE_INSENSITIVE").is_err();
        match args.next() {
            Some(arg) => {
                if arg == "1" {
                    case_sensitive = true;
                } else {
                    case_sensitive = false;
                }
            }
            None => (),
        };

        println!("{:?}", case_sensitive);

        println!("sensitive{}", case_sensitive);
        Ok(Config {
            query,
            filename,
            case_sensitive,
        })
    }
}
pub fn run(config: &Config) -> Result<(), Box<dyn Error>> {
    let contents: String = fs::read_to_string(&config.filename)?;
    // println!("With text:\n{}", contents);
    let res = if config.case_sensitive {
        search(&config.query, &contents)
    } else {
        search_case_insensitive(&config.query, &contents)
    };
    for line in res {
        println!("{}", line)
    }
    Ok(())
}
pub fn search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
    // let mut results = Vec::new();

    // for line in contents.lines() {
    //     if line.contains(query) {
    //         results.push(line);
    //     }
    // }
    // return results;
    contents
        .lines()
        .filter(|line| line.contains(query))
        .collect()
}
pub fn search_case_insensitive<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
    let mut results: Vec<&str> = Vec::new();
    let query = query.to_lowercase();
    for line in contents.lines() {
        if line.to_lowercase().contains(&query) {
            results.push(line);
        }
    }
    results
}
